Influence of surfactants on the structure of titanium oxide gels : experiments and simulations

We report here on experimental and numerical studies of the influence of surfactants on mineral gel synthesis. The modification of the gel structure when the ratios water-precursor and water-surfactant vary is brought to the fore by fractal dimension measures. A property of {\em polydispersity of the initial hydrolysis} is proposed to explain these results, and is successfuly tested through numerical experiments of three dimensional chemically limited aggregation.Comment: 12 pages, 4 Postscript figures, uses RevTe

Xq27 FRAXA locus is a strong candidate for dyslexia: evidence from a genome-wide scan in French families.

Dyslexia is a frequent neurodevelopmental learning disorder. To date, nine susceptibility loci have been identified, one of them being DYX9, located in Xq27. We performed the first French SNP linkage study followed by candidate gene investigation in dyslexia by studying 12 multiplex families (58 subjects) with at least two children affected, according to categorical restrictive criteria for phenotype definition. Significant results emerged on Xq27.3 within DYX9. The maximum multipoint LOD score reached 3,884 between rs12558359 and rs454992. Within this region, seven candidate genes were investigated for mutations in exonic sequences (CXORF1, CXORF51, SLITRK2, FMR1, FMR2, ASFMR1, FMR1NB), all having a role during brain development. We further looked for 50 UTR trinucleotide repeats in FMR1 and FMR2 genes. No mutation or polymorphism co-segregating with dyslexia was found. This finding in French families with Dyslexia showed significant linkage on Xq27.3 enclosing FRAXA, and consequently confirmed the DYX9 region as a robust susceptibility locus. We reduced the previously described interval from 6.8 (DXS1227–DXS8091) to 4 Mb also disclosing a higher LOD score

Investigating trophic ecology and dietary niche overlap among morphs of Lake Trout in Lake Superior

Four morphs of Lake Trout (Salvelinus namaycush, Walbaum 1792) have been identified in Lake Superior: leans, siscowets, humpers, and redfins. In this comprehensive study, the trophic ecology of Lake Trout morphs were characterized using stomach content, fatty acid, and stable isotope data. Stomach content results indicated a predominately piscivorous diet for leans, siscowets, and redfins, whereas humper diets were comprised of 50% fish and 50% Mysis by mass. Humper and siscowets were most similar in their dietary fatty acid profiles, whereas redfins had the most distinct dietary fatty acid profile. Results from stable isotope analysis revealed some among-morph differences along a pelagic-profundal consumption gradient (34S), but there were no significant differences in trophic position (15N) or basal carbon sources among morphs (13C). Using the recently developed nicheROVER software package, 4-dimensional trophic niches for each morph were quantified using stable isotope ratios (δ13C, δ15N, and δ34S) and fatty acid profiles (30 dietary fatty acids, condensed to one axis). Humpers had the largest 4-dimensional niche regions of all four morphs, and redfins had the smallest. Pairwise probability of overlap among morphs in these four-dimensional niche regions was determined to be < 50% in most cases. Overall, stomach content results indicate that humpers diets were more planktivorous than the other morphs, consistent with previous research. Results of the niche overlap analysis suggests some degree of generalist feeding for all morphs. Better characterization of seasonal variation in diet using tracers that reflect more recent feeding (e.g., fatty acids, stomach contents, and/or stable isotope analyses performed on tissues that turnover more quickly than muscle) are needed to further elucidate among-morph differences and similarities in diet and trophic ecology

Propriété foncière, exploitation agricole et aménagement de l'espace rural

[eng] Landownership, farming and country-planning - Towards 1970 appears gradualy a new trend of the French agricultural structure policy, simultaneously with the birth of a country planning policy. Concerning landownership, the policy of helping the farmers to buy the land declines in favour of a policy who attempts to attract non-farmers invests. Farming becomes a plurality of activities, i.e. the agricultural policy accepts the compatibility of agricultural and non-agricultural activities ; a policy of rejuvenating the farmers is connected to an increasing care of local population equilibrium ; farming becomes a more vocational activity ; at the same time the farming definition includes more and more the target of maintening rural spaces. All these new practices induce progressively the concept of specific action areas. By this way, the agricultural structure policy, properly so called, becomes in connection with the course of country planning policy who attempts to organize the diffusion of urbanization through rural space as to distribute whole of national activities. [fre] On peut situer aux environs des années 1970 (l'émergence d'une nouvelle orientation dans la politique des structures des exploitations agricoles, et la naissance d'une politique d'aménagement de l'espace rural. En matière de propriété foncière, c'est l'abandon progressif d'une politique qui favorisait l'acquisition des terres par les agriculteurs, pour une politique d'ouverture à d'investissement foncier non agricole. L'exploitation agricole s'ouvre à la pluri-activité, c'est-à-dire à d'exercice d'activités non spécifiquement agricoles ; une politique de rajeunissement des chefs d'exploitation plus systématique se lie à un souci croissant d'équilibre démographique régional ; l'activité agricole se professionnalise ; elle inclut de plus en plus dans sa définition d'objectif d'entretien de l'espace naturel. L'ensemble de ces nouvelles pratiques conduit peu à peu à la notion des zones spécifiques d'intervention. Par là, la politique agricole proprement dite rejoint le courant de l'aménagement de d'espace rural, qui vise à organiser le mouvement de diffusion de l'urbanisation sur une large partie du territoire agricole, et la répartition de l'ensemble des activités.

Contrats de mariage et régimes matrimoniaux

Egalement paru dans : Document de travail INSEE-Direction des Statistiques démographiques et sociales : "Le patrimoine des ménages en 1992", F 9508 (dossier de 4 articles, document à statut intermédiaire)National audienceEn France, 16 % des couples établissent un contrat au moment de leur mariage, 3 % dans les années qui suivent, soit au total 19 % des couples mariés. La fréquence des contrats augmente avec le niveau de patrimoine et varie selon les régions : le Nord et l'Est, suivis du Sud-Ouest, arrivent en tête. Même si l'on ne fait pas explicitement de contrat, on bénéficie d'un régime matrimonial, celui de la communauté réduite aux acquêts : 89 % des couples sont dans ce cas. Parmi les couples qui font un contrat au moment de leur mariage, certains choisissent aussi la communauté légale ou un régime voisin (7,4 %), d'autres la séparation des biens ou la communauté universelle. Ce dernier régime est rarement choisi au moment du mariage, sauf en Alsace : il est plutôt établi lors d'un changement de régime, après une longue vie commune, en l'absence d'enfant, et concerne 3,3% des couples. La séparation des biens (6,3 %) est le régime traditionnel des milieux d'indépendants mais aussi, de plus en plus, celui des couples les plus "modernes", soit qu'ils soient jeunes, soit qu'il s'agisse de remariage, quand la femme est diplômée et/ou active : il se rapproche par là des couples non mariés